What is the most abundant gas in the Earth's atmosphere?

The most abundant gas in the Earth's atmosphere is nitrogen, which comprises about 78% of the atmosphere by volume. Nitrogen is a colorless, odorless gas that plays a crucial role in various biological and chemical processes, including the nitrogen cycle, which is essential for plant growth and sustenance.

In contrast, oxygen, while vital for most life forms and making up about 21% of the atmosphere, is not as abundant as nitrogen. Carbon dioxide and argon are present in even smaller amounts, with carbon dioxide typically around 0.04% and argon about 0.93%. Thus, nitrogen is not only the most abundant gas, but it also acts as a filler that helps to moderate the concentration of other gases, making it a significant component of the atmosphere.